There is known an internal combustion engine of a vehicle, which is provided with an EGR device to recirculate a portion of exhaust gas as EGR gas to an intake passage for the purpose of improving fuel consumption and reducing exhaust emissions. Furthermore, it is also known to execute a fuel cut control operation and an idle reduction control operation. The fuel cut control operation is an operation that stops combustion of the internal combustion engine by stopping fuel injection upon satisfaction of a fuel cut condition at the time of, for example, decelerating the engine (thereby decelerating the vehicle). The idle reduction control operation is an operation that stops combustion of the internal combustion engine by stopping the fuel injection and/or ignition of the fuel upon satisfaction of an idle reduction condition.
However, in the internal combustion engine, which is provided with the EGR device, when the combustion stop control operation, such as the fuel cut control operation or the idle reduction control operation, which stops the combustion of the internal combustion engine, is executed, the EGR gas remains in the intake passage even upon closing of the EGR valve. Therefore, at the time of restarting the engine after the execution of the combustion stop control operation (after stopping of the combustion of the engine), a large quantity of the EGR gas may possibly flow into a cylinder of the engine. When a quantity of the EGR gas, which flows into the cylinder at the time of restarting the engine, exceeds an EGR limit (an upper limit value of the quantity of the EGR gas, which can be combusted normally), the combustion state may possibly become unstable, thereby possibly deteriorating the restartability of the engine.
In view of the above point, JP2009-191643A teaches the following technique. Specifically, the timing, at which the fuel cut condition is satisfied, is predicted based on traffic information of a road, along which the vehicle travels. A control operation (e.g., an operation of controlling an opening degree of the EGR valve to a closing side thereof), which reduces a quantity of the EGR gas present in the intake system of the internal combustion engine, is executed at a time point, which is earlier than the predicted timing of the satisfying of the fuel cut condition by a predetermined time period.
However, according to the technique of JP2009-191643A, although the operation of reducing the quantity of the EGR gas present in the intake system is executed, JP2009-191643A does not teach or suggest a function of determining a quantity of the EGR gas, which actually flows into the cylinder. Therefore, there is a possibility of that the quantity of the EGR gas, which flows into the cylinder at the time of restarting the engine after the execution of the combustion stop control operation, is not sufficiently reduced. In such a case, the combustion state may become unstable, thereby possibly resulting in the deterioration of restartability of the engine.